A door mirror for reflecting what is behind the vehicle's body is installed as a kind of safety device on the outside surface of a motor vehicle's door on each side of the driver's seat.
In general, however, there exists a driver's blind spot behind the vehicle's body, which is not reflected in the door mirror. When altering the reflection angle of the mirror so as to make such blind spot visible, an antinomic problem occurs of permitting a spot having been visible to become a blind spot. Accordingly, to make sure of the safety behind the vehicle's body with the door mirror, care must be taken of the above characteristic of the mirror. In addition, there has occurred another problem that when adjusting the reflection angle of the mirror so as to make visible what is in the distance behind the vehicle's body, it becomes difficult to view the rear wheel portion so as to prevent the vehicle from running onto the shoulder of a road due to the difference in distance from the shoulder between the front wheel and the rear wheel.
Further, when two vehicles pass each other on a narrow road or when a vehicle is put in a small garage, the door mirror is often folded so as to make the vehicle's width as small as possible; however, this also causes a problem in that once the door mirror is folded, what is behind the vehicle's body, that has been seen in the mirror until then, becomes completely invisible, making it difficult to make sure of the safety behind the vehicle's body.
Still further, when adjusting the reflection angle of the mirror so as to make visible what is in the distance behind the vehicle's body, as described above, it also becomes difficult to make sure of the safety around the rear wheels, causing a problem of permitting accidents, such as wheels' coming off, to be more likely to occur.
In order to overcome these problems, there have been proposed some types of door mirrors: for example, proposed in Japanese Unexamined Patent Publication No. 2000-272419 is a door mirror of which mirror surface has its outer portion convexly curved to broaden the driver's view so that the driver's blind spot is decreased as much as possible; and proposed in Japanese Unexamined Patent Publication No. 2000-108782 is a door mirror of which side surface has another mirror affixed thereon so that it can be used, when the door mirror is fold down, to see what is behind the vehicle's body and make sure of the safety there.
However, in the former invention, that is, the door mirror of which mirror surface has its outer portion convexly curved to broaden the driver's view, since the flat mirror surface, as a main portion, and the convexly curved mirror surface are continuously formed, the images reflected in the door mirror seem to the driver to change from a natural state at the main portion to a distorted state at the outer portion, which causes a problem of making the images less readable, and moreover, a problem of the driver's getting confused by the distortedly changing images and being unable to look carefully frontward.
Further, even with such a door mirror, the problem cannot be overcome of making invisible what is in the distance behind the vehicle's body when adjusting the reflection angle of the door mirror to make the rear wheels and their vicinities visible with an intention of preventing the rear wheels from running onto the shoulder of a road.
In the latter invention, that is, the door mirror of which side surface has another smaller mirror affixed thereon, when using the door mirror in the unfolded state, the smaller mirror affixed on its side surface is not only useless for making sure of the safety behind the vehicle's body, but liable to be an obstacle of other drivers' safe driving because it reflects in an unexpected direction the sunlight or headlamp lights of oncoming cars. Further, such a door mirror has another problem of being more likely to come in contact with some other things during the vehicle's moving, and once having come in contact with others, it is easily broken, as a result, it will never be able to be utilized again.